TCI Tricone Bit IADC637/635 Introduction The TCI (Tungsten Carbide Insert) Tricone Bit IADC637/635 is a rotary rock drilling tool engineered for hard formations with high compressive strength, including limestone, conglomerate, dolomite and flint. Three rotating cones with tungsten carbide inserts provide stable penetration, balanced load distribution and reduced vibration, delivering reliable drilling performance in demanding mining, water well and exploration projects.